The idea of high-speed magnetically levitated trains has floated around since the early 1900s. The concept involves using magnetic fields to levitate a train above the rails, or guideways. No contact between wheels and rails means less friction, and, in theory, lower maintenance costs compared to conventional bullet trains.
The technology has seen real-world operation, notably in German and Japanese demonstration projects, and in 2004 Shanghai launched the first commercial maglev line after two years of trials. Connecting the Shanghai airport to downtown, the Shanghai Maglev Train (pictured here) travels up to a blazing-fast 431 kilometers per hour, or about 268 miles per hour.
But the up-front costs are steep. In 2008, Germany ditched plans for a 40-kilometer (24.9 mile) maglev project in Munich after cost estimates ballooned to more than 3 billion euros, from a previous estimate of 1.85 billion euros. But maglev isn't over and out yet. This spring, Japanese officials gave the go-ahead for construction of a 9-trillion-yen ($111.4 billion), 320-mile (515-kilometer) maglev line between Tokyo and Osaka, much of it underground. If all goes according to plan-and maglev projects rarely do-the two cities will be connected by a 40-minute train ride by 2045.